Desafíos de la datificación de la salud en Uruguay durante la pandemia de COVID-19

Silvia Méndez: Universidad de la República, Facultad de Medicina, Grupo Uruguayo Interdisciplinario de Análisis de Datos de COVID-19. Unidad Académica de Bioética, Mag. en Derechos de Infancia y Políticas Públicas -- Horacio Botti: Universidad de la República, Facultad de Medicina, Grupo Uruguayo Interdisciplinario de Análisis de Datos de COVID-19. Departamento de Biofísica, Laboratorio de Biofísica Integrativa, Dr. en Medicina y Biología

Expression, crystallization and preliminary X-ray crystallographic analysis of glucose-6-phosphate dehydrogenase from the human pathogen Trypanosoma cruzi in complex with substrate. Corrigendum

A correction to the article by Ortíz et al. [(2011), Acta Cryst. F67, 1457–1461]

Design, Synthesis and Biological Characterization of Potential Antiatherogenic Nitric Oxide Releasing-Tocopherol Analogs.

PostprintSynthesis and biological characterization of a series of tocopherol analogs with NO-releasing capacity are reported. The selected NO-donor moieties were nitrooxy and furoxan. All products were tested for their in vitro NO-releasing capacities, vasodilating properties and antiplatelet activity. They were also capable to prevent LDL oxidation

Allosteric Activation of Bacterial Response Regulators: the Role of the Cognate Histidine Kinase Beyond Phosphorylation

Response regulators are proteins that undergo transient phosphorylation, connecting specific signals to adaptive responses. Remarkably, the molecular mechanism of response regulator activation remains elusive, largely because of the scarcity of structural data on multidomain response regulators and histidine kinase/response regulator complexes. We now address this question by using a combination of crystallographic data and functional analyses in vitro and in vivo, studying DesR and its cognate sensor kinase DesK, a two-component system that controls membrane fluidity in Bacillus subtilis. We establish that phosphorylation of the receiver domain of DesR is allosterically coupled to two distinct exposed surfaces of the protein, controlling noncanonical dimerization/tetramerization, cooperative activation, and DesK binding. One of these surfaces is critical for both homodimerization- and kinase-triggered allosteric activations. Moreover, DesK induces a phosphorylation-independent activation of DesR in vivo, uncovering a novel and stringent level of specificity among kinases and regulators. Our results support a model that helps to explain how response regulators restrict phosphorylation by small-molecule phosphoryl donors, as well as cross talk with noncognate sensors.Fil: Trajtenberg, Felipe. Instituto Pasteur de Montevideo; UruguayFil: Albanesi, Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Biología Molecular y Celular de Rosario; Argentina. Universidad Nacional de Rosario, Facultad de Ciencias Bioquímicas y Farmacéuticas; ArgentinaFil: Ruetalo, Natalia. Instituto Pasteur de Montevideo; UruguayFil: Botti, Horacio. Instituto Pasteur de Montevideo; UruguayFil: Mechaly, Ariel. Instituto Pasteur de Montevideo; Uruguay. Institut Pasteur, Unité de Microbiologie Structurale, Paris; FranciaFil: Nieves, Marcos. Instituto Pasteur de Montevideo, Laboratorio de Biología Celular de Membranas, Montevideo; UruguayFil: Aguilar, Pablo Sebastián. Instituto Pasteur de Montevideo, Laboratorio de Biología Celular de Membranas, Montevideo; UruguayFil: Cybulski, Larisa Estefania. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Biología Molecular y Celular de Rosario; Argentina. Universidad Nacional de Rosario, Facultad de Ciencias Bioquímicas y Farmacéuticas; ArgentinaFil: Larrieux, Nicole. Instituto Pasteur de Montevideo; UruguayFil: de Mendoza, Diego. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Biología Molecular y Celular de Rosario; Argentina. Universidad Nacional de Rosario, Facultad de Ciencias Bioquímicas y Farmacéuticas; ArgentinaFil: Buschiazzo, Alejandro. Instituto Pasteur de Montevideo; Uruguay. Institut Pasteur, Département de Biologie Structurale et Chimie, Paris; Franci

Reacciones y efectos de radicales libres y oxidantes biológicos a nivel molecular : formación controlada por distancia de peroxinitrito y modulación alostérica redox en la albúmina humana

Tribunal: Dr. Luis Acerenza, Dr. Gustavo Salinas, Dr. Balaraman Kalyanaraman

Glucose-6-Phosphate Dehydrogenase from the Human Pathogen Trypanosoma cruzi Evolved Unique Structural Features to Support Efficient Product Formation

International audienceGlucose-6-phosphate dehydrogenase (G6PDH) is the key enzyme supplying reducing power (NADPH) to the cells, by oxidation of glucose-6-phosphate (G6P), and in the process providing a precursor of ribose-5-phosphate. G6PDH is also a virulence factor of pathogenic trypanosomatid parasites. To uncover the biochemical and structural features that distinguish TcG6PDH from its human homolog, we have solved and analyzed the crystal structures of the G6PDH from Trypanosoma cruzi (TcG6PDH), alone and in complex with G6P. TcG6PDH crystallized as a tetramer and enzymatic assays further indicated that the tetramer is the active form in the parasite, in contrast to human G6PDH, which displays higher activity as a dimer. This quaternary structure was shown to be particularly stable. The molecular reasons behind this disparity were unveiled by structural analyses: a TcG6PDH-specific residue, R323, is located at the dimer-dimer interface, critically contributing with two salt bridges per subunit that are absent in the human enzyme. This explains why TcG6PDH dimerization impaired enzyme activity. The parasite protein is also distinct in displaying a 37-amino-acid extension at the N-terminus, which comprises the non-conserved C8 and C34 involved in the covalent linkage of two neighboring protomers. In addition, a cysteine triad (C53, C94 and C135) specific of Kinetoplastid G6PDHs proved critical for stabilization of TcG6PDH active site. Based on the structural and biochemical data, we posit that the N-terminal region and the catalytic site are highly dynamic. The unique structural features of TcG6PDH pave the way toward the design of efficacious and highly specific anti-trypanosomal drugs

Swapping FAD binding motifs between plastidic and bacterial ferredoxin-NADP(H) reductases.

International audiencePlant-type ferredoxin-NADP(H) reductases (FNRs) are grouped in two classes, plastidic with an extended FAD conformation and high catalytic rates and bacterial with a folded flavin nucleotide and low turnover rates. The 112-123 β-hairpin from a plastidic FNR and the carboxy-terminal tryptophan of a bacterial FNR, suggested to be responsible for the FAD differential conformation, were mutually exchanged. The plastidic FNR lacking the β-hairpin was unable to fold properly. An extra tryptophan at the carboxy terminus, emulating the bacterial FNR, resulted in an enzyme with decreased affinity for FAD and reduced diaphorase and ferredoxin-dependent cytochrome c reductase activities. The insertion of the β-hairpin into the corresponding position of the bacterial FNR increased FAD affinity but did not affect its catalytic properties. The same insertion with simultaneous deletion of the carboxy-terminal tryptophan produced a bacterial chimera emulating the plastidic architecture with an increased k(cat) and an increased catalytic efficiency for the diaphorase activity and a decrease in the enzyme's ability to react with its substrates ferredoxin and flavodoxin. Crystallographic structures of the chimeras showed no significant changes in their overall structure, although alterations in the FAD conformations were observed. Plastidic and bacterial FNRs thus reveal differential effects of key structural elements. While the 112-123 β-hairpin modulates the catalytic efficiency of plastidic FNR, it seems not to affect the bacterial FNR behavior, which instead can be improved by the loss of the C-terminal tryptophan. This report highlights the role of the FAD moiety conformation and the structural determinants involved in stabilizing it, ultimately modulating the functional output of FNRs